Dennis Mersereau

This dust devil at the Rocky Mountain Arsenal in Colorado occurred during a controlled burn on March 14. Nobody was injured during the fire or the dust devil, which lofted hundreds of tumbleweeds into the air and burned an extra acre of land.

Dust devils form when a column of hot air begins to rapidly rise and rotate. As the column of rising air begins to vertically stretch out, it starts rotating faster (think of an ice skater pulling her arms in while spinning around) and turns into a dust devil.